# 3D airborne EM with metallic casing

**URL:** <https://simpeg.discourse.group/t/3d-airborne-em-with-metallic-casing/535>\
**Category:** Electromagnetics\
**Created:** [December 12, 2023, 5:41pm UTC](https://simpeg.discourse.group/t/3d-airborne-em-with-metallic-casing/535 "2023-12-12T17:41:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![geodriz](https://avatars.discourse-cdn.com/v4/letter/g/e9a140/32.png) [@geodriz](https://simpeg.discourse.group/u/geodriz)\
**Post date:** [December 12, 2023, 5:41pm UTC](https://simpeg.discourse.group/t/3d-airborne-em-with-metallic-casing/535/1 "2023-12-12T17:41:53Z")

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Hi All,

I’m currently performing some fwd controlled source EM tests over simple 3D models, and I  
started with FDEM 3D using the ‘plot\_fwd\_3\_fem\_3d.py’ script, from the SimPEG/tutorials/fdem repository. The results look promising, and as future step, I’d like to investigate more complicated cases,  
including a metallic casing in the model. I have a couple of questions about this point.

In Heagy et al, 2017, one of the tests was accomplished by using a magnetic dipole in a borehole;  
maybe, for an airborne FDEM, could I use a cylindrical mesh (coaxial with the borehole)  
and set the magnetic dipole at the Tx height (above the borehole head)? What I want to do is to  
consider the metallic casing as a “passive” feature.

The second question is if this test could also be done for TDEM, using suitable scripts from  
the EM packages. I have seen that the “plot\_fwd\_2\_tem\_cyl.py” script is also available,  
so perhaps, the experiment could be implemented?

Please notice that I’m just wondering if this tasks could be done using the available package, and not  
if there is some ready script to do it. I understand that there could be much work to do.

Thank you.